Process for vulcanizing rubber and product obtained thereby



Patented Apr. 7, 1925.

UNITED STATES PATENT OFFICE.

SIDNEY M. CADWELL, 0F LEONIA, NEW JERSEY, ASSIGNOR TO THE NAUGATUCKCHEMICAL COMPANY, A CORPORATION OF CONNECTICUT.

PROCESS FOR 'VULCANIZING RUBBER AND PRODUCT OBTAINED THEREBY.

No Drawing.

To all whom it may concern:

Be it known that I, SID a citizen of the United Leonia, county of Bergen5 sey, have invented certainnew Application filed January 10, 1922.Serial No. 528,278.

NEY M. CADWELL, States, residing in State of New J erand usefulImprovements in Processes for Vulcanizing Rubber and Products which thefollowing exact description.

Obtained Thereby, of is a full, clear, and

This invention relates to processes for vulcanizing rubber and toproducts obtained thereby. It is more vulcanization b pounds.

particularly directed to' y organic sulphur com- This application is. acontinuation in part ofm vulcanizing agents avoiding the y co-pendingapplication Serial No. 359,807, filed February 19, 1920.

One objectof the inventio n is to provide a process of the kin dmentioned employing obtainable from inexerials by a simple. method. ofthe invention is to pron which vulcanizing agents ntioned may bereadilycomrubber or similar material, rmit 'of the carrying out of at ordinarytemperatures in generation of 0 process of vulcanization,

takes place when sulphur 0 Another object of the in vide a series oforganic ing agents having a stab is, adapted to remain as compositionfor a time. Another obj to provide a series erally desirable such ashigh tensi ageing, resistance shall be su'bstanti of the vulcanizin beror in thin sheets while acids during the 1 as, for example, hloride isused.

vention is to prosulphur vulcanizle character, that such withoutdeconsiderable period of ect of the invention is of products havinggenphysical characteristics, le strength, resistance to to flexing,etc., and which ally free from the odor g ingredients employed.

The invention accordingly consists broad and product obtained ing rubberor similar ly in In this formula X valent element or the process,

v.therefrom, for treat material, which co rubber to an organ avulcani'zing agent con ic sul mprises subjecting the phur compound astaining the group represents any biradical such as sulphur, oxygen,etc., In the table herein shown If forming part of the specificationthis group appears joined to the element R which may or may not be partof another group. The group thus appears as RCSSCR, it

where R may be any element, preferably nitrogen, oxygen, sulphur orcarbon 'attached to the carbon of the formula.

It is to be noted that the group formula represents enerally derivativesof carbon oxy sulphi e or carbon disulphide. They may be convenientlydesignated as disulphides.

It will be understood that the invention is not limited to the speciesshown in the accompanying table, tuting other elements than nitrogen,carbon,-oxygen and sulphur therein shown at tached to the carbon of theformula for the symbol R, various other species may be formulated fallinwithin the scope of the invention.

Although the various species disclosed are represented as symmetrical,it will be understood that unsymmetrical species also fall within thelimits of the invention.

The table is and that by substi-- 1. or ss o 2. ot zsspo a. OfiIJSSCO,4. opssgo s s NR NR CR: R11

9. spssps 10. s c ss s 11. spssr s 12. sgssos 3 O 0 NR NR R2 R:

1a. NfiSSfiN 14.NCSS(|'|JN 15.N("3SS|JN 16.NCSSON s s 0 NR NR more Ingeneral the various species set forth above are able to vulcanize'bothhot and cold and may be used for such vulcanization in thick masses ofrubber, in thin sheets or in cements. The general procedure invulcanizing employing the various species is as follows: 100 parts ofrubber, parts of a compound containing a combined metal M, 2 parts of anamine, and 10 parts of the vulcanizing agent are mixed. hotvulcanization is employed, the usual tards the cure considerably.

temperatures or lower may be used for periods of 30 minutes or more tocomplete vulcanization. If cold vulcanization is desired the mixedmaterials may be allowed to stand at ordinary temperature for a week orless when vulcanization is complete. The procedure just given may beemployed with thin or thick masses of rubber and in the case of cementswhere a solvent is used with the mixture, the procedure after mixing andevaporation of the solvent, is substantially identical with thatemployed for thin masses of rubber.

In general the use of bases, particularly amines, is preferred inconnection with members, of this group. The action of the addition ofprimary and secondary amines to materials of this class has been foundto be as follows :-The acceleration by aliphatic amines is greatest whenapproximately three-quarters molecular weight of the amine on the basisof the carbon disulphide content of the thiol salt is used. An excess ofprimary aliphatic amines re- An excess of secondary aliphatic amineretards the cure less. The greater the amount of primary aromatic amineadded, the greater the acceleration. Tertiary amines have substantiallyno effect. Dibenzyl amine has given excellent results in theacceleration of vulcanization according to the invention. Sodiumhydroxide also accelerates the action of disulphides. The combined metalM may be added as the oxide or as any other desired compound, such asthe xanthogenate, dithiobenzoate, acetate or in other forms ofcombination. For cold vulcanization the combined metals which have beenfound to be suitable are: zinc or mercury, preferably in the mercuricform. Of these two, zinc is preferred. If vulcanization above ordinarytemperatures is carried out the preferred metals are the following:zinc, mercury, preferably in the mercuric form, lead, preferably in theplumbous form, cadmium, copper, preferably in the cupric form, arsenic,preferably in the arsenous form, magnanese, preferably in the manganousform.

Species 1.

ocssoo ll II S s As an example of the specific procedure employingmembers of this group, 100 parts of rubber are mixed by milling with 20parts of zinc oxide, 2 parts of aniline and 10 parts of O-normal butylthiocarbonic acid disulphide. The .mixture is allowed to stand at roomtemperature for several days, at the end of which time vulcanization iscomplete. If the same mixture is placed in in a mold under steampressure at approximately 40 pounds per square inch vulcanization isaccomplished in approximately 30 minutes. Hot vulcanization may becontinued for longer periods if desired without harmful effects. Thetime required for vulcanization is of course dependent on the thicknessof the rubber and will vary with different kinds of rubber. l

By varying the amine various results may be produced and the temperaturenecessary for vulcanization may be likewise varied.

By the term low temperature as here employed is meant temperaturesranging from room temperature or lower to 100 C.

The above vulcanizing agent is a preferred member of a group ofcompounds which are able to produce approximately equally good results.Among other members of this species may be mentioned the following:

O-methyl thiocarbonic acid disulphide O-ethyl thiocarbonic aciddisulphide oznbopsspocm. s s O-amyl thiocarbonic acid disulphideoaiuopsspoofirm Other thiocarbonic acid disulphides containing otheralkyl or equivalent groups will also cause vulcanization in a similarmanner, but these substances will naturally vary in their effectsaccording to the nature of the alkyl or similar groups, and they may beselected for the requirements of a particular case.

By the use of the above mentioned vulcanizing agents, vulcanization isaccomplished in a rapid and eflicient manner, and rubber products areproduced having high tensile strength, good ageing qualities and verylittle odor. The fact that many of the members of the above species areoily substances renders their addition to the coinpounding ingredientson the mill an easy operation and results in a very uniform andefficient mixture. The raw materials from which the substances areprepared are moreover cheap and the process very simple.

It is therefore evident that the objects of I the invention aboveenumerated are thus achieved.

A particular merit of these vulcanizing ingredients is that they willproduce vulcanization, and that they will do so with out regenerating anacid, which is an advantage not possessed by sulphur chloride for thisagent generates hydrochloric acid. They may be added directly to thecompounding ingredients on the mixing mill which is impracticable withsulphur chloride.

Species 2.

ocssoo ll 0 o The following member of this species has been employed togive good results in connection with the process included in theinvent1on:

connection with the process included in the 1nvention:

benzoyldisulphide Will provide a vulcanized product having asweet odor.

Species 6'.

oossoo (II l The following members of this species have been employed togive good results in connection with the process included in theinvention Acetyldisulphide omo-ssoon, ll

0 o Ilienzoyldisulphide CnHsF-S-SFCoHr.

Species .9.

sossps l s The following member of this species has been employed togive good results in connection with the invention Dibutylthiolester ofthioncarbonyldisulphide C4Hv$-$ 5 |3SC4H0 s 8 process included in the-Species 13.

NossoN i i Members of this class include:Dimethyldiphenylthiuramdisulphide CH3 CH3 ll II CoHls S S ceHsDiethyldiphenylthiuramdisulphide CzHa (EH5 CuHaDiparamethylphenylenedimethylthiuramdisulphide p. CH5-COH4 vention'Ietraethylcarbamyldisulphide 0621.011. p. -s-s-c :-N

The members of the various species mentioned will vulcanize slowlyeither at low or high temperatures without added amines. In generaladded amines accelerate vulcanization with these vulcanizing agents.

As an alternative of the examples given for the vulcanization of rubberabove, the following mixture is representative of a mass vulcanizing ateither high or low temperatures: 100 parts of rubber, 10 parts of zincoxide, 2 parts of dibenzyl amine, 10 parts of O-normal butylthiocarbonic acid disulphide. This mixture is preferably vulcanized atelevated temperatures, that is at say 4L0 lbs. steam pressure. At suchtemperature satisfactory vulcanization occurs in approximately minutes.For low temperature vulcanization the mixture given above if allowed tostand for approximately one week at ordinary temperature will vulcanizesatisfactorily.

The accelerators which may be employed with vulcanizing agents of thetype herein described include both inorganic and organic materials,preferably bases," such as amines, hydroxides, oxides, etc.

The stocks prepared in accordance with the procedures outlined aboveemploying material of the class herein described have in general thevarious advantages of sulphur cured stocks. Due "to the low content ofsulphur which is secured through the use of materials of this class, andparticularly due to the fact that substantially all of this sulphur ispresent in the rubber in the combined state, as has been shown up-onanalysis of these stocks, the stocks are free from bloom and haveexcellent ageing properties. Using materials herein recited withaccelerators of the kind mentioned, air cured translucent stocks may beobtained.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit thereof, it will be understoodthat I do not intend to limit myself to the specific embodiment hereinset forth except as indicated in the appended claims.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group ossc,

II II X X and vulcanizing the rubber.

2. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group ossc,

s s and vulcanizing the rubber.

3. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group RCSSCR, ll ll x X and vulcanizing the rubber.

4. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group agossc m, and vulcanizing the rubber.

5. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group and an amine, and vulcanizing the rubber. 6. A process fortreating rubber, which comprises subjecting the rubber to an organicsulphur compound as a vulcanizing agent characterized by the group ossoll I! s s and an amine, and vulcanizing the rubber.

and an amine, and vulcanizing the rubber.

9. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group in the presence of a combined metal M, and

vulcanizing the rubber.

10. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group in the presence of a combined metal M, and vulcanizing therubber.

11. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group RCSSOR,

it X in the presence of a combined metal M, and vulcanizing the rubber.

12. A process for treating rubber, which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group RCSSCR,

I It

s in the presence of a combined metal M, and vulcanizing the rubber.

13. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent comprising thegroup and vulcanizing the rubber.

14. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group ossc,

in the presence of combined zinc, and vulcanizing the rubber.

15. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent characterized bythe group npsspn in the presence of combined zinc, and vulcanizing therubber.

16. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent comprising thegroup ocssco.

- in the presence of combined zinc, and vulcanizing the rubber.

' 17. A process for treating rubber whichcomprises sub ecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulammoossc ioomt 1": x and vulcanizing the rubber.

18. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulaI oimoossoomm,

and vulcanizing the rubber.

19. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulain the presence of an amine, and vulcanizing the rubber.

20. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulaOAHIO CSSCOCJI in the presence of an aromatic amine, and vulcanizing therubber.

21. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulaC(H OOSSCOOIH in the presence of a combined metal M, and

vulcam zing the rubber.

22. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulaC4HnOCSSCOC4Hn,

g in the presence of combined zinc, and vul canizing the rubber.

23. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulain the presence of an amine and-combined zinc, and vulcanizing therubber.

24. A process for treating rubber which comprises subjecting the rubberto an organic sulphur compound as a vulcanizing agent having the formulaCAHaOCSSCOCAHn, '5'; t

.in the presence of aniline and combined zinc,

and vulcanizing the rubber.

25. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the group osso.

26. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the groupv 0. t27. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the group I nsson.

28. A vulcanized rubber derived fromandanamine.

31. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the groupacssos,

and an amine.

32. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the group nossr a, x x

in the presence of a combined metal M.

36. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the groupnossoa, ll [I s s in the resence of a combined metal M. 37 vulcanizedrubber derived from *rubber combined with an organic sulphur compound asa vulcanizing agent comprising the group 38. A vulcanized rubber derivedfrom rubber combined with an organic sulphur compound as a vulcanizingagent characterized by the group osso,

in the ipresence of combined zinc.

39. vulcanized rubber derived from -rubber combined with an organicsulphur compound as a vulcanizing agent charac' terized by the groupRCSSCR. ll II in the resence of combined zinc.

40. vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent comprlsmg the group oossco, ll ls in the resence of combined zinc.

41. vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formula mmor sspiooim.

42. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formula olmoc ismomm.

43. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formula in thepresence of an amine.

44. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formula cmoossoooim.

in the presence of an aromatic amine.

45. A vulcanized r'ubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formulaOlIInOCSSCOClHQ,

in the presence of a combined metal M.

4.6. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formula mmo isspomm.

in the presence of combined zinc.

47 A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formula lOO in thepresence of an amine and combined zinc.

48'. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent having the formula in thepresence of aniline and combined zinc. 49. A process for treating rubberwhich comprises subjecting the rubber to an organic sulphur compound asa vulcanizing agent characterized by the group osso lit

in the presence of an amine and a combined metal M', and vulcanizing therubber. 50. A process for treating rubber which comprises subjecting therubber to an orgame sulphur compound as a vulcanlzing agentcharacterized by the group csso in the presence of an amine and acombined in the presence of an amine and a combined metal M, andvulcanizing the rubber.

53., A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the group cssoI] II x x in the presence of an amine and a combined metal M.

54. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the group osso[I ll in the presence of an amine and a combined metal M.

55. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the group ossct i in the presence of an amine and combined zinc.

56. A vulcanized rubber derived from rubber combined with an organicsulphur compound as a vulcanizing agent characterized by the group,

ll S in the presence of an amine and a combined metal M.

Signed at New York, New York, this 7 day of January, 1922.

SIDNEY M. CADWELL.

